1. Technical Field
The present invention relates to a virtual image display device that presents an image as a virtual image to an observer, and specifically to a virtual image display device preferable for a head-mounted display worn on a head of the observer.
2. Related Art
Various systems have been proposed as optical systems incorporated in virtual image display devices such as a head-mounted display (hereinafter, also referred to as HMD) worn on a head of an observer (for example, see Patent Document 1 (JP-A-2011-2753), Patent Document 2 (JP-A-2010-145859), or the like).
Regarding the virtual image display device including HMD, reduction in size and weight and achievement of a wider angle of view without deterioration of image quality are desired. If the entire field of view of the observer is covered and only image light is seen, the observer does not grasp the outside world condition and feels uneasy. The outside world and the image are superimposed and seen, and thereby, new application such as virtual reality is created. Accordingly, a display that superimposes and displays image light without hindering the vision of the outside world is desired. Further, for improvement of the feel when being worn by the observer and better physical appearance, it is generally desirable to make the form closer to spectacles.
In consideration of the above described situation, for example, it is conceivable that a virtual image display device includes a light guide part provided in front of the observer's eye to see through, and the see-through type light guide part guides image light from an image display element to the eye of the observer. In this type of virtual image display device, it is necessary to support the light guide part in front of the eye of the observer, and, for example, a pair of image display units each including an image light generator and a light guide plate are fixed to a coupling member and the coupling member is fixed to the back of a frame similar to a spectacle frame (see Patent Document 1).
However, in the virtual image display device disclosed in Patent Document 1 or the like, the coupling member is provided separately from the frame to support the image display unit and the structure becomes complicated, the weight increases if the support strength for the image display unit by the coupling member is increased, and, if the weight of the coupling member or the like is reduced, the support strength of the image display unit is liable to be lower.